/*** WARNING - THIS CODE HAS NOT BEEN FINISHED! ***/
/*** The original PPPD code is written in a way to require either the UNIX DES
     encryption functions encrypt(3) and setkey(3) or the DES library libdes.
     Since both is not included in lwIP, MSCHAP currently does not work! */
/*****************************************************************************
* chpms.c - Network MicroSoft Challenge Handshake Authentication Protocol program file.
*
* Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
* Copyright (c) 1997 by Global Election Systems Inc.  All rights reserved.
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice and the following disclaimer are included verbatim in any
* distributions. No written agreement, license, or royalty fee is required
* for any of the authorized uses.
*
* THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************
* REVISION HISTORY
*
* 03-01-01 Marc Boucher <marc@mbsi.ca>
*   Ported to lwIP.
* 97-12-08 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
*   Original based on BSD chap_ms.c.
*****************************************************************************/
/*
 * chap_ms.c - Microsoft MS-CHAP compatible implementation.
 *
 * Copyright (c) 1995 Eric Rosenquist, Strata Software Limited.
 * http://www.strataware.com/
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Eric Rosenquist.  The name of the author may not be used to
 * endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/*
 * Modifications by Lauri Pesonen / lpesonen@clinet.fi, april 1997
 *
 *   Implemented LANManager type password response to MS-CHAP challenges.
 *   Now pppd provides both NT style and LANMan style blocks, and the
 *   prefered is set by option "ms-lanman". Default is to use NT.
 *   The hash text (StdText) was taken from Win95 RASAPI32.DLL.
 *
 *   You should also use DOMAIN\\USERNAME as described in README.MSCHAP80
 */

#define USE_CRYPT

#include "lwip/opt.h"

#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */

#if MSCHAP_SUPPORT /* don't build if not configured for use in lwipopts.h */

#include "ppp_impl.h"
#include "pppdebug.h"

#include "md4.h"
#ifndef USE_CRYPT
	#include "des.h"
#endif
#include "chap.h"
#include "chpms.h"

#include <string.h>


/*************************/
/*** LOCAL DEFINITIONS ***/
/*************************/


/************************/
/*** LOCAL DATA TYPES ***/
/************************/
typedef struct {
	u_char LANManResp[24];
	u_char NTResp[24];
	u_char UseNT; /* If 1, ignore the LANMan response field */
} MS_ChapResponse;
/* We use MS_CHAP_RESPONSE_LEN, rather than sizeof(MS_ChapResponse),
   in case this struct gets padded. */



/***********************************/
/*** LOCAL FUNCTION DECLARATIONS ***/
/***********************************/

/* XXX Don't know what to do with these. */
extern void setkey(const char*);
extern void encrypt(char*, int);

static void DesEncrypt(u_char*, u_char*, u_char*);
static void MakeKey(u_char*, u_char*);

#ifdef USE_CRYPT
	static void Expand(u_char*, u_char*);
	static void Collapse(u_char*, u_char*);
#endif

static void ChallengeResponse(
    u_char* challenge, /* IN   8 octets */
    u_char* pwHash,    /* IN  16 octets */
    u_char* response   /* OUT 24 octets */
);
static void ChapMS_NT(
    char* rchallenge,
    int rchallenge_len,
    char* secret,
    int secret_len,
    MS_ChapResponse* response
);
static u_char Get7Bits(
    u_char* input,
    int startBit
);

static void
ChallengeResponse(u_char* challenge,  /* IN   8 octets */
                  u_char* pwHash,    /* IN  16 octets */
                  u_char* response   /* OUT 24 octets */)
{
	u_char    ZPasswordHash[21];

	BZERO(ZPasswordHash, sizeof(ZPasswordHash));
	BCOPY(pwHash, ZPasswordHash, 16);

#if 0
	log_packet(ZPasswordHash, sizeof(ZPasswordHash), "ChallengeResponse - ZPasswordHash", LOG_DEBUG);
#endif

	DesEncrypt(challenge, ZPasswordHash +  0, response + 0);
	DesEncrypt(challenge, ZPasswordHash +  7, response + 8);
	DesEncrypt(challenge, ZPasswordHash + 14, response + 16);

#if 0
	log_packet(response, 24, "ChallengeResponse - response", LOG_DEBUG);
#endif
}


#ifdef USE_CRYPT
static void
DesEncrypt(u_char* clear,  /* IN  8 octets */
           u_char* key,   /* IN  7 octets */
           u_char* cipher /* OUT 8 octets */)
{
	u_char des_key[8];
	u_char crypt_key[66];
	u_char des_input[66];

	MakeKey(key, des_key);

	Expand(des_key, crypt_key);
	setkey((char*)crypt_key);

#if 0
	CHAPDEBUG(LOG_INFO, ("DesEncrypt: 8 octet input : %02X%02X%02X%02X%02X%02X%02X%02X\n",
	                     clear[0], clear[1], clear[2], clear[3], clear[4], clear[5], clear[6], clear[7]));
#endif

	Expand(clear, des_input);
	encrypt((char*)des_input, 0);
	Collapse(des_input, cipher);

#if 0
	CHAPDEBUG(LOG_INFO, ("DesEncrypt: 8 octet output: %02X%02X%02X%02X%02X%02X%02X%02X\n",
	                     cipher[0], cipher[1], cipher[2], cipher[3], cipher[4], cipher[5], cipher[6], cipher[7]));
#endif
}

#else /* USE_CRYPT */

static void
DesEncrypt(u_char* clear,  /* IN  8 octets */
           u_char* key,   /* IN  7 octets */
           u_char* cipher /* OUT 8 octets */)
{
	des_cblock    des_key;
	des_key_schedule  key_schedule;

	MakeKey(key, des_key);

	des_set_key(&des_key, key_schedule);

#if 0
	CHAPDEBUG(LOG_INFO, ("DesEncrypt: 8 octet input : %02X%02X%02X%02X%02X%02X%02X%02X\n",
	                     clear[0], clear[1], clear[2], clear[3], clear[4], clear[5], clear[6], clear[7]));
#endif

	des_ecb_encrypt((des_cblock*)clear, (des_cblock*)cipher, key_schedule, 1);

#if 0
	CHAPDEBUG(LOG_INFO, ("DesEncrypt: 8 octet output: %02X%02X%02X%02X%02X%02X%02X%02X\n",
	                     cipher[0], cipher[1], cipher[2], cipher[3], cipher[4], cipher[5], cipher[6], cipher[7]));
#endif
}

#endif /* USE_CRYPT */


static u_char
Get7Bits(u_char* input, int startBit)
{
	register unsigned int  word;

	word  = (unsigned)input[startBit / 8] << 8;
	word |= (unsigned)input[startBit / 8 + 1];

	word >>= 15 - (startBit % 8 + 7);

	return word & 0xFE;
}

#ifdef USE_CRYPT

/* in == 8-byte string (expanded version of the 56-bit key)
 * out == 64-byte string where each byte is either 1 or 0
 * Note that the low-order "bit" is always ignored by by setkey()
 */
static void
Expand(u_char* in, u_char* out)
{
	int j, c;
	int i;

	for(i = 0; i < 64; in++) {
		c = *in;

		for(j = 7; j >= 0; j--) {
			*out++ = (c >> j) & 01;
		}

		i += 8;
	}
}

/* The inverse of Expand
 */
static void
Collapse(u_char* in, u_char* out)
{
	int j;
	int i;
	unsigned int c;

	for(i = 0; i < 64; i += 8, out++) {
		c = 0;

		for(j = 7; j >= 0; j--, in++) {
			c |= *in << j;
		}

		*out = c & 0xff;
	}
}
#endif

static void
MakeKey(u_char* key,     /* IN  56 bit DES key missing parity bits */
        u_char* des_key /* OUT 64 bit DES key with parity bits added */)
{
	des_key[0] = Get7Bits(key,  0);
	des_key[1] = Get7Bits(key,  7);
	des_key[2] = Get7Bits(key, 14);
	des_key[3] = Get7Bits(key, 21);
	des_key[4] = Get7Bits(key, 28);
	des_key[5] = Get7Bits(key, 35);
	des_key[6] = Get7Bits(key, 42);
	des_key[7] = Get7Bits(key, 49);

#ifndef USE_CRYPT
	des_set_odd_parity((des_cblock*)des_key);
#endif

#if 0
	CHAPDEBUG(LOG_INFO, ("MakeKey: 56-bit input : %02X%02X%02X%02X%02X%02X%02X\n",
	                     key[0], key[1], key[2], key[3], key[4], key[5], key[6]));
	CHAPDEBUG(LOG_INFO, ("MakeKey: 64-bit output: %02X%02X%02X%02X%02X%02X%02X%02X\n",
	                     des_key[0], des_key[1], des_key[2], des_key[3], des_key[4], des_key[5], des_key[6], des_key[7]));
#endif
}

static void
ChapMS_NT(char* rchallenge,
          int rchallenge_len,
          char* secret,
          int secret_len,
          MS_ChapResponse* response)
{
	int      i;
	MDstruct  md4Context;
	u_char    unicodePassword[MAX_NT_PASSWORD * 2];
	static int  low_byte_first = -1;

	LWIP_UNUSED_ARG(rchallenge_len);

	/* Initialize the Unicode version of the secret (== password). */
	/* This implicitly supports 8-bit ISO8859/1 characters. */
	BZERO(unicodePassword, sizeof(unicodePassword));

	for(i = 0; i < secret_len; i++) {
		unicodePassword[i * 2] = (u_char)secret[i];
	}

	MDbegin(&md4Context);
	MDupdate(&md4Context, unicodePassword, secret_len * 2 * 8);  /* Unicode is 2 bytes/char, *8 for bit count */

	if(low_byte_first == -1) {
		low_byte_first = (PP_HTONS((unsigned short int)1) != 1);
	}

	if(low_byte_first == 0) {
		/* @todo: arg type - u_long* or u_int* ? */
		MDreverse((unsigned int*)&md4Context);  /*  sfb 961105 */
	}

	MDupdate(&md4Context, NULL, 0);  /* Tell MD4 we're done */

	ChallengeResponse((u_char*)rchallenge, (u_char*)md4Context.buffer, response->NTResp);
}

#ifdef MSLANMAN
static u_char* StdText = (u_char*)"KGS!@#$%";  /* key from rasapi32.dll */

static void
ChapMS_LANMan(char* rchallenge,
              int rchallenge_len,
              char* secret,
              int secret_len,
              MS_ChapResponse*  response)
{
	int      i;
	u_char    UcasePassword[MAX_NT_PASSWORD]; /* max is actually 14 */
	u_char    PasswordHash[16];

	/* LANMan password is case insensitive */
	BZERO(UcasePassword, sizeof(UcasePassword));

	for(i = 0; i < secret_len; i++) {
		UcasePassword[i] = (u_char)toupper(secret[i]);
	}

	DesEncrypt(StdText, UcasePassword + 0, PasswordHash + 0);
	DesEncrypt(StdText, UcasePassword + 7, PasswordHash + 8);
	ChallengeResponse(rchallenge, PasswordHash, response->LANManResp);
}
#endif

void
ChapMS(chap_state* cstate, char* rchallenge, int rchallenge_len, char* secret, int secret_len)
{
	MS_ChapResponse response;
#ifdef MSLANMAN
	extern int ms_lanman;
#endif

#if 0
	CHAPDEBUG(LOG_INFO, ("ChapMS: secret is '%.*s'\n", secret_len, secret));
#endif
	BZERO(&response, sizeof(response));

	/* Calculate both always */
	ChapMS_NT(rchallenge, rchallenge_len, secret, secret_len, &response);

#ifdef MSLANMAN
	ChapMS_LANMan(rchallenge, rchallenge_len, secret, secret_len, &response);

	/* prefered method is set by option  */
	response.UseNT = !ms_lanman;
#else
	response.UseNT = 1;
#endif

	BCOPY(&response, cstate->response, MS_CHAP_RESPONSE_LEN);
	cstate->resp_length = MS_CHAP_RESPONSE_LEN;
}

#endif /* MSCHAP_SUPPORT */

#endif /* PPP_SUPPORT */
